2015—2019年辽宁省麻疹病毒基因型及流行株血凝素基因特征分析

Measles virus genotype and hemagglutinin gene characteristics of epidemic strains in Liaoning Province,China from 2015 to 2019

目的对辽宁省2015—2019年麻疹病毒基因型及流行株血凝素(hemagglutinin,H)基因特征进行分析,为实现消除麻疹目标提供科学依据。方法对2015—2019年获得的53株麻疹病毒(或原始标本),采用RT-PCR法扩增N基因羧基末端450个核苷酸片段,进行基因定型,并对流行的麻疹毒株H基因全长1 854个片段进行核苷酸和氨基酸序列变异分析。结果 2015—2019年辽宁省共检测到H1a、A和D8 3个基因型病毒,分离到30株麻疹病毒,其中29株为H1a基因亚型,并分为2个分支:Cluster1和Cluster2。H蛋白与疫苗株相比,遗传距离有逐年增大趋势,且在个别氨基酸功能位点上发生了变异,Cluster1所有毒株均在第397位发生了氨基酸的替换,由脯氨酸(Pro P)突变成亮氨酸(Leu L)。结论辽宁省2015—2019年流行的麻疹病毒以H1a基因型为主,且存在不同年份之间麻疹毒株的持续循环传播。H1a基因型麻疹毒株大部分重要的氨基酸功能位点均保持稳定,我国使用的麻疹疫苗对目前流行的麻疹毒株仍具有较好的保护效果。

Objective To analyze the genotype of measles virus and genetic characteristics of hemagglutinin(H) of epidemic strains in Liaoning Province,China from 2015 to 2019 so as to provide a scientific basis for the elimination of measles.Methods Fifty-three measles virus strains(or original specimens)obtained from 2015 to 2019 were genotyped by reverse transcription polymerase chain reaction(RT-PCR) amplification of 450 nucleotides at C-terminus of N gene.The nucleotide and amino acid sequence variations of H gene of a circulating measles virus strain,at a full length of1 854 nucleotides,were analyzed.Results From 2015 to 2019,three genotypes of measles virus,H1a,A and D8,were detected in Liaoning Province,and 30 measles virus strains were isolated,of which 29 were of genotype H1a and divided into two branches(Clusters 1 and 2).Compared with that of the vaccine strain,the genetic distance of H protein increased year by year,and there were variations in individual amino acid functional sites.All the strains of Cluster 1 had amino acid substitution of Proline(Pro P)with Leucine(Leu L)at site 397.Conclusion The measles virus circulating in Liaoning Province from 2015 to 2019 was dominated by the genotype H1a,and there was continuous circulating transmission of measles virus strains between different years.Most of the important amino acid functional sites of measles virus strains of genotype H1a were stable,and the measles vaccine used in China still has a good protective effect on the currently circulating measles virus strains.